Mine also split at around 70,000 miles. I picked up a new seat cover from the dealership (around 2016-2017ish) at $180 and swapped it out. Around the end of 2019 it cracked again. Both times it happened during the winter and with the second seat I used a vinyl conditioner. It’s really the only issue I’ve had with the car other than the gas door being a PITA every once and a while, oh and the oil consumption issue that Subaru says is a nonissue.
If I keep the car and or it lasts another couple years I’ll spend the money on Katzkin seats.